Work based learning is an educational approach for secondary and postsecondary students that provide opportunities to achieve employment- related competencies in the workplace, actually it provides students with knowledge and skills that help them connect school experiences to real-life work activities. Work-based learning is often undertaken in conjunction with classroom or related learning, and may take the form of work placements, work experience, workplace mentoring, instruction in general workplace competencies, and broad instruction in all aspects of industry.

(Adapted from NCVER - See definition below)
Source: UNEVOC community

Programs for both secondary and postsecondary students which provide opportunities to achieve employment-related competencies in the workplace. Work-based learning is often undertaken in conjunction with classroom or related learning, and may take the form of work placements, work experience, workplace mentoring, instruction in general workplace competencies, and broad instruction in all aspects of industry.
Source: NCVER 2013, Australia

acquisition of knowledge and skills through carrying out – and reflecting on – tasks in a vocational context, either at the workplace (such as alternance training) or in a VeT institution.
Source: CEDEFOP 2014, Europe

Learning taking place through carrying out and reflecting on work tasks in a real environment
Source: EU commission (NRDC) 2011, Europe